Premium
Ionization equilibria of dicarboxylic acids in dimethyl sulfoxide as studied by NMR
Author(s) -
Choi Paul J.,
Petterson Krag A.,
Roberts John D.
Publication year - 2002
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.488
Subject(s) - chemistry , intramolecular force , steric effects , dimethyl sulfoxide , hydrogen bond , solvent , dicarboxylic acid , bicyclic molecule , medicinal chemistry , stereochemistry , computational chemistry , organic chemistry , molecule
The ionization equilibria of dicarboxylic acids measured by K 1 / K 2 are expected to be substantially influenced by stabilization of the monoanion through intramolecular hydrogen bonding. However, except in sterically favorable cases, such as with maleic, 3,4‐furandicarboxylic, 2,3‐bicyclo[1.2.2]heptadienedicarboxylic and diethylmalonic acids, the K 1 / K 2 values for other dicarboxylic acids, where intramolecular hydrogen bonding of the monoanion might be expected, are relatively small at ∼100 in water. This research uses NMR to corroborate and extend the pioneering conductance measurements of K 1 / K 2 of dicarboxylic acids by Kolthoff and coworkers with dimethyl sulfoxide (DMSO) as solvent. In extending these measurements, we have determined K 1 / K 2 for 3,4‐furandicarboxylic ( 1 ) and 2,3‐bicyclo[1.2.2]heptadienedicarboxylic ( 2 ) acids, because these were predicted by McCoy to be especially sterically favorable for intramolecular hydrogen bonding in the form of their monoanions and, indeed, we have found K 1 / K 2 values for these acids in DMSO of 1 × 10 15 and 4 × 10 16 respectively. In contrast, the corresponding value for succinic acid is about 10 8 . Copyright © 2002 John Wiley & Sons, Ltd.